var path = require('path');
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var fs = require('fs');
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var utils = require('./utils');
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var del = require('./del');
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var writeJSON = utils.writeJSON;
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var cache = {
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/**
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* Load a cache identified by the given Id. If the element does not exists, then initialize an empty
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* cache storage. If specified `cacheDir` will be used as the directory to persist the data to. If omitted
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* then the cache module directory `./cache` will be used instead
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*
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* @method load
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* @param docId {String} the id of the cache, would also be used as the name of the file cache
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* @param [cacheDir] {String} directory for the cache entry
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*/
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load: function (docId, cacheDir) {
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var me = this;
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me._visited = {};
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me._persisted = {};
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me._pathToFile = cacheDir ? path.resolve(cacheDir, docId) : path.resolve(__dirname, '../.cache/', docId);
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if (fs.existsSync(me._pathToFile)) {
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me._persisted = utils.tryParse(me._pathToFile, {});
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}
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},
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/**
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* Load the cache from the provided file
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* @method loadFile
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* @param {String} pathToFile the path to the file containing the info for the cache
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*/
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loadFile: function (pathToFile) {
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var me = this;
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var dir = path.dirname(pathToFile);
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var fName = path.basename(pathToFile);
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me.load(fName, dir);
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},
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/**
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* Returns the entire persisted object
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* @method all
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* @returns {*}
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*/
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all: function () {
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return this._persisted;
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},
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keys: function () {
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return Object.keys(this._persisted);
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},
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/**
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* sets a key to a given value
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* @method setKey
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* @param key {string} the key to set
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* @param value {object} the value of the key. Could be any object that can be serialized with JSON.stringify
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*/
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setKey: function (key, value) {
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this._visited[key] = true;
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this._persisted[key] = value;
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},
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/**
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* remove a given key from the cache
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* @method removeKey
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* @param key {String} the key to remove from the object
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*/
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removeKey: function (key) {
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delete this._visited[key]; // esfmt-ignore-line
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delete this._persisted[key]; // esfmt-ignore-line
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},
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/**
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* Return the value of the provided key
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* @method getKey
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* @param key {String} the name of the key to retrieve
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* @returns {*} the value from the key
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*/
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getKey: function (key) {
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this._visited[key] = true;
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return this._persisted[key];
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},
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/**
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* Remove keys that were not accessed/set since the
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* last time the `prune` method was called.
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* @method _prune
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* @private
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*/
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_prune: function () {
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var me = this;
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var obj = {};
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var keys = Object.keys(me._visited);
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// no keys visited for either get or set value
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if (keys.length === 0) {
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return;
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}
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keys.forEach(function (key) {
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obj[key] = me._persisted[key];
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});
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me._visited = {};
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me._persisted = obj;
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},
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/**
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* Save the state of the cache identified by the docId to disk
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* as a JSON structure
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* @param [noPrune=false] {Boolean} whether to remove from cache the non visited files
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* @method save
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*/
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save: function (noPrune) {
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var me = this;
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!noPrune && me._prune();
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writeJSON(me._pathToFile, me._persisted);
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},
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/**
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* remove the file where the cache is persisted
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* @method removeCacheFile
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* @return {Boolean} true or false if the file was successfully deleted
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*/
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removeCacheFile: function () {
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return del(this._pathToFile);
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},
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/**
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* Destroy the file cache and cache content.
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* @method destroy
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*/
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destroy: function () {
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var me = this;
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me._visited = {};
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me._persisted = {};
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me.removeCacheFile();
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},
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};
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module.exports = {
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/**
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* Alias for create. Should be considered depreacted. Will be removed in next releases
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*
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* @method load
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* @param docId {String} the id of the cache, would also be used as the name of the file cache
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* @param [cacheDir] {String} directory for the cache entry
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* @returns {cache} cache instance
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*/
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load: function (docId, cacheDir) {
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return this.create(docId, cacheDir);
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},
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/**
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* Load a cache identified by the given Id. If the element does not exists, then initialize an empty
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* cache storage.
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*
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* @method create
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* @param docId {String} the id of the cache, would also be used as the name of the file cache
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* @param [cacheDir] {String} directory for the cache entry
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* @returns {cache} cache instance
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*/
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create: function (docId, cacheDir) {
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var obj = Object.create(cache);
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obj.load(docId, cacheDir);
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return obj;
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},
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createFromFile: function (filePath) {
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var obj = Object.create(cache);
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obj.loadFile(filePath);
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return obj;
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},
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/**
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* Clear the cache identified by the given id. Caches stored in a different cache directory can be deleted directly
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*
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* @method clearCache
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* @param docId {String} the id of the cache, would also be used as the name of the file cache
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* @param cacheDir {String} the directory where the cache file was written
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* @returns {Boolean} true if the cache folder was deleted. False otherwise
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*/
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clearCacheById: function (docId, cacheDir) {
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var filePath = cacheDir ? path.resolve(cacheDir, docId) : path.resolve(__dirname, '../.cache/', docId);
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return del(filePath);
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},
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/**
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* Remove all cache stored in the cache directory
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* @method clearAll
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* @returns {Boolean} true if the cache folder was deleted. False otherwise
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*/
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clearAll: function (cacheDir) {
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var filePath = cacheDir ? path.resolve(cacheDir) : path.resolve(__dirname, '../.cache/');
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return del(filePath);
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},
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};
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